Electric water heater



Sept. 16. 1924.

J. A. M DONALD ELECTRIC WATER HEATER Filed Sept. 28, 1922 INVENTE'JR.

Patented Sept. 16, 1924. I

UNITED STATES PATENT OFFICE.

ELECTRIC WATER HEATER.

Application filed September 28 1822. Serial 1T0. 591,062.

To all whom it may concern:

Be it known that 1, JAMES ALEXANDER MACDONALD, of the city of Brantford,county of Brant, Province of Ontario, Canada, a subject of the King ofGreat Britain, have invented certainnew and useful Improvements inElectric Water Heaters, of which the following is a specification.

This invention relates to heaters adapted for heating water, andparticularly to that type used in heating water in domestic hot waterboilers. The object of the invention is to devise a construction whichis interchangeable so that it may be used in various Ways, as forexample, by being inserted directly in the interior of a hot waterboiler, or by being mounted singly or in sets in a separate casingmounted alongside the boiler.

I A further object is to devise a construction of heatin element by theuse of which greater e ciency will be obtained for the amount of currentused.

Another object is to so arrange the heating element in its housing thatit may be removed, and replaced with a similar element or with anelement of larger or smaller capacity without in any way interferingwith the water connections of the boiler or casing, and to so arrangethe connections that the connections outside the boiler or casing areinsulated from the heat from the element, and also to so arrange thedevice that moisture from outside is prevented from working in to theinterior of the element housing.

The above mentioned and other objects are attained by means of theconstructions hereinafter described and illustrated in the accompanyingdrawings in which Fig. 1 is a longitudinal section of the improvedheater as mounted ori the interior of a'domestic hot water boiler;

Fig. 2 a cross section through the heating element; and

Fig. 3 a cross section through the housing. In the drawings likenumerals of reference indicate corresponding parts in the differentfigures.

1 is part of which is provided with the usual threaded opening in itsside. 2 is the housing for the heater, which housing is preferablyformed of brace tubing and has one closed the shell of a hot waterboiler,

end. To the open end of the housin 2 is secured the sleeve 3, having athreade portion thereon adapted to fit the -threaded opening in theboiler 1.

On the end of this sleeve 3 is cast a band 4 preferably of aluminum, thesleeve being provided with grooves or recesses 5 in which the metal oftheband is adapted to run to anchor the band on the sleeve. The wrenchused for installing the device is applied to this band 4, and there istherefore no danger of distorting or damaging the housing 2 or sleeve 3by the wrench. I

It will be noted on reference to the drawings that the exterior surfaceof the housing is provided With a series of corrugations 6, whichcorrugations may be formed as a spiral thread. These corrugations notonly increase the heating area of the housing, but it is found'inpractice that a housing provided with these corrugations is not nearlyso liable to twist or warp, as a housing without these corrugations.

The heating element comprises a core or base 7, preferably of soapstoneas this material possesses two important features not found in porcelainwhich has heretofore mainly been used for this purpose. One of thesefeatures is thatthe soapstone more rapidly absorbs and conducts heatfrom the resistance and the other feature is that it retains the heatfora considerable time once it has become saturated.

In this core 7 are formed, by machining, a plurality of longitudinalslits 8, and in these slits is wound the resistance winding 9. Thisresistance winding is formed as a ribbon and is set on edge in theslits.- At least sufiicient high temperature heat conducting dielectriccementis then placed in the slits to properly hretain the resistancewinding in place. I on the setting of the cement has reached a certainpoint, the current is turned on the resistance winding and as it expandsit forces back the cement sufliciently to always give the winding roomfor expansion. The winding is then at perfeet liberty to expand in theslits and there is therefore no dan er of the winding suffering from anyun ue expansion strains.

To hold the resistance winding in place while the cement is being filledin the slits and setting, annular grooves 10 are formed in the core andin each of these grooves a thread is wound over the resistancewindtemperature of the resistance winding and the higher temperatureimparted to the core is thatthe heater operates With greater speed andefliciency and there is not-the danger of the winding burning out.

At one end of the core is formed, preferably integral therewith, thespacer 11 to hold the core spaced from the closed end of the housing-2.At the other end of the core preferably integral'therewith is formed theblockv 12 and in each side of this block is formed a groove 13. The endsof the resist.- ance winding 9 are led one into each of these grooves; v

Heretofore it has usually been the practice to provide suitable boltsand nuts for seto the leads. Due to temperature stresses and other causesfthese bolts and nuts in 5. tightly with asbestos fibre 16. The outsideand while doingso is preheated, and when it strikes the hot solid end ofthe soapstone core it is further preheated, and there is therefore nodanger of moist air passing through into theinterior of the housing to Icondense and drop on to the resistance winding, and there is thus alsoavoided the usual noise caused by condensation within the housing.

To prevent the heat from the device being conducted. to the connectionsoutside the *tanks, washers 17 of asbestos or like material are placedbetween the ends of the sleeve 8 66 and band 4 and the end of theconnector 18.

of sufiicient size for the passage of the wires 14. The connector 18 issecured in position by screws 19' passing through the washers 1'7 intothe end of the band 4.

22 is a condulet the end of'whichis adapt- .seen that a compact andeffective arrangelnent has been devised; that there is no ne- 'having avery long life.

curing the ends of the resistance winding v -of a core of refractorynon-conducting maair passes very slowly through this packing,

These washers are provided with holes only wires 21.

From the construction described it will be cessity of removing thehousing once it is in position; that the heating element is easilyremoved and replaced if necessary; that there is little danger of moistair working into the interior of the housing; that the outsideconnections are well heat insulated from the heating element; andfinally that the method ,of mounting the winding on the core is onewhich will result'in the winding As stated in the preamble of thespecification, it will be understood that the heater might be mounted ina separate casing from the water tank or that two or more heaters may bemounted in a single casing, and in the latter case the heaters will beso con-- nected'that one or more may be used as desired to give a'numberof different heats.

What I claim as my invention is 1. In'an electric heater, thecombination of a substantially solid cylindrical core of refractorynonconducting material having a plurality of narrow slitsformedlongitudinally thereof; and a resistance element of lesser depththan and mounted in said slits, said resistance being held in the bottomof the slits by dielectric cement.

2. In-an electric heater, the combination terial having a plurality ofslits formed longitudinally thereof; and a resistance element mounted insaid slits, said slits being closed by dielectric cement, said element,being free to expand in said slits. 3. In an electric heater, thecombination of a substantially solid cylindrical core of refractorynon-conducting material having a plurality of narrow slits formedlongitudinally thereof; and a ribbon resistance element of lesser widththan the depth of the slits and set im edge in said' slits, saidresistance being held in the bottom of the slits by dielectric cement. q

4. In an electric heater, the combination of a core ofrefractorynon-conductin material having a plurality of slits forme1ongitudinally thereof; and a ribbon resistance element set on edge "insaid slits, said slits being closed by dielectric cement, said ele mentbeing free to expand. H 4 5. The process of forming an electricheaterhaving a core of refractory non-conducting material having slits formedlongitudinally thereof; which consists in winding a resistance elementin said slits; placing dielectric cement in said slits tohold theelement in position; and supplying current to the element before thesetting of the cement is complete.

6. The process of forming an electric heater having ducting materialwhich consists in machining slits in said core longitudinally thereof;

winding a resistance element in said slits;

placing dielectric cement in said slits to old the-element in position;and supplying current to the element before the setting of the cement iscomplete.

7. The process of forming an electric heater having a core of refractorynon-conducting material havin slits formed longitudinally thereof whicconsists in winding a ribbon resistance element on the edge in saidslits; placing dielectric cement in said slits to hold the element inposition; and supplying current to the element before the setting of thecement is complete.

8. In an electric heater, the combination of a housing having one closedend; a solid removable core of refractory non-conducting material insaid housing, a space being left at the open end of the housing; aresistance element on said core; lead wires connected with theresistance element; means for closing the .open end of the housing,-

said space being packed with a loose fibrous non-conducting material.

' 9. In an electric heater, the combination of a housing; a core ofrefractory non-conductingmaterial in said housing; a resistance elementon said core; a tting into which lead wires may be led; means connectingthe fitting to the housing;- said fitting being heat insulated from thehousing.

10. In an electric heater, the combination of a housing for a heatingelement; a fitting into which lead wires may be led; means connecting,the an asbestos washer between the housing and the fitting.

11. In an electric heater, the combination of a housing; a core ofrefractory non-conducting material in said housing; and aresistanceelement on said core, said housing being provided with a series ofcorrugations on its outer surface. t

12. In an electric heater the combination of a housing; a core ofrefractory non-conducting material in said housing; and a resistanceelement on said core, said housing being provided with a series ofcircumferential corrugations.

' heater, the combination 13. In an electric of a housing for a heatingelement, said housing having a threaded portion on its outer surfaceslightly spaced from one end and grooves'inthe outer surface of the end;and a band cast on said end and anchored in said grooves.

acore of refractory non-con-' fitting to the housing; andv .element seton edge in said 14. In an electric heater, the combination of a core ofrefractory non-conducting material; a resistance element on said core;and lead wires connected with the the resistance element, the lead wiresand the ends of the element being integrally united.

15. In an electric heater, the combination of a housing and a core ofrefractory nonconducting material: a resistance element on said core;

said housing and connected with the ends ofthe resistance element, thelead wires and the ends of the element being integrally united.

16. In an electric heater, the combination of a core of refractorynon-conducting material; a resistance element on said core, said corebeing provided with grooves adjacent one end into which the ends of theresistance element are led; lead wires extending into said grooves andconnected with the ends of the resistance element, the wires andelements-being integrally united, said grooves being packed to enclosethe joints between the wires and elements.

17. In an electric heater, the combination of a housing for a heatingelement, said housing being provided with a series of corrugations onits outer surface; a conduit for lead wires; means connecting theconduit to the housing; and means for checking the passa e of heat fromthe housing to the condui 18. In an electric heater, thecombination of ahousing and a core of refractory nonconducting material; a heatingelement; and lead wires extending into said housing ends of and leadwires extending into and connected with the ends of the resistthecombination.

terial having a plurality of slits formed longitudinally thereof; aribbon resistance slits, said resistance being held in position bydielectric cement; and lead wires connected with the ends of theresistance element; the lead wires and the ends of the element beingintegrally united.

20. In an electric heater, the combination of a core of refractory,non-conducting material having a plurality of slits formedlongitudinally thereof; and a ribbon resistance element set on edge insaid slits, said resistance being held in place with dielectric cement,said core also being provided with grooves adjacent one end into whichthe ends of the resistance element are led; lead wires entending intosaid grooves and connected with the ends of the resistance element, thewires and elements mg' nwith the resistance element; means for closv 7face of the tegrally united, said to. enclose the joints element.

21. In an electric-heater, the combination of a housing having oneclosedend; a ,re movable core of refractory non-conducting material insaid housing, a space being left at the open end of the housing; aresistance element on said core; lead wires connected with theresistance element; means for closing the open end of the housing, beingpacked to check the admission of moisture to the interior of thehousing, said housing being provided with a series of one rugations onits outer surface.

22. In an electric heater, the combination of a housing, for a heatingelement, said housing having a threaded portion on its outer surfaceslightly spaced from one end and grooves in the outer surface of theend; and a band cast on said end and anchored in said grooves, theremainder of the outer surhousing being provided with a series ofcorrugations.

23. In an .electric heater, the combination of a housing having oneclosed end: a removable core of refractory .non conducting material insaid housing .a space being left atthe open end of the housing; aresistance element on said core; lead wires connected between the wiresand ingthe open end of the housing, said space being packed to check theadmission of grooves being packed said space 1 moisture to the interiorof the housing; and a conduit secured to said housing, said firstmentioned means being adapted to prevent liieatpassing from the housingto the conuit.

24. In an electric heater, the combination of a housing having oneclosed end; a removable core of refractory non-conducting material insaid housing, a space being left at the open end of the housing; aresistance united with the resistance element;

said space being packed to check the admis sion of moisture to theinterior of the housmg.

25. In an electric heater, the combination of a housing, for a housinghaving a threaded portion on its outer surface adjacent one end, saidend having an irregular outer surface; and a band cast'on said endhaving the irregular outer surface.

26. In an electric heater, the combination of a housing for a heatingelement; a fitting into which lead wires may be led; means connectingthe fitting to the housing, said fitting being adapted to be rotarilyadjustable relative to the housing, said fitting being heat insulatedfrom the housing.

Signed at Brantford, Ont., this 18th da-v of September, 1922.

'- JAMES ALEXANDER mnnomw housing,

heating element, said

